fig02: The vertical axis shows the mean percentage choice of the tobacco- versus chocolate-seeking response [± standard error of the mean (SEM)] during the Pavlovian to instrumental transfer (PIT) test (50% = equal choice or indifference). The horizontal axis shows the stimulus that was presented on the screen before a response choice was made: either no-stimulus, an image of a plain pack (Fig. 1a) or a branded pack (Fig. 1b). In both experiments, the branded pack stimulus primed tobacco-seeking more than the no-stimulus and plain pack conditions, and the latter two conditions did not differ

Mentions:
One participant was excluded for reporting inaccurate knowledge of the response–outcome contingencies following concurrent choice acquisition, leaving a final sample of n = 23 for analysis. These participants had a mean age of 20.8 years [standard deviation (SD) = 2.3, range = 18–27] and smoked an average of 9.3 cigarettes on smoking days (SD = 5.7, range = 1–25). Table 1 and Fig. 2a show the percentage choice of the tobacco- versus the chocolate-seeking response in the three stimulus conditions of the PIT test. ANOVA with these data (see Table 2) produced a main effect of stimulus (F(2,44) = 3.44, P = 0.04, ŋp2 = 0.14). Crucially, that there was no evidence of a difference in tobacco-seeking between the plain pack and the no-stimulus condition (F(1,22) = 0.97, P = 0.33, ŋp2 = 0.04). This critical result was confirmed by a Bayes factor of 0.38, indicating low confidence in this difference. Accordingly, the plain and no-stimulus conditions were averaged, and the branded pack enhanced tobacco-seeking above this average (F(1,22) = 7.23, P = 0.01, ŋp2 = 0.25). The failure of the plain packs to elicit tobacco-seeking in the PIT test, in contrast to branded packs, demonstrates that the discriminative control function of plain packs is degraded.

fig02: The vertical axis shows the mean percentage choice of the tobacco- versus chocolate-seeking response [± standard error of the mean (SEM)] during the Pavlovian to instrumental transfer (PIT) test (50% = equal choice or indifference). The horizontal axis shows the stimulus that was presented on the screen before a response choice was made: either no-stimulus, an image of a plain pack (Fig. 1a) or a branded pack (Fig. 1b). In both experiments, the branded pack stimulus primed tobacco-seeking more than the no-stimulus and plain pack conditions, and the latter two conditions did not differ

Mentions:
One participant was excluded for reporting inaccurate knowledge of the response–outcome contingencies following concurrent choice acquisition, leaving a final sample of n = 23 for analysis. These participants had a mean age of 20.8 years [standard deviation (SD) = 2.3, range = 18–27] and smoked an average of 9.3 cigarettes on smoking days (SD = 5.7, range = 1–25). Table 1 and Fig. 2a show the percentage choice of the tobacco- versus the chocolate-seeking response in the three stimulus conditions of the PIT test. ANOVA with these data (see Table 2) produced a main effect of stimulus (F(2,44) = 3.44, P = 0.04, ŋp2 = 0.14). Crucially, that there was no evidence of a difference in tobacco-seeking between the plain pack and the no-stimulus condition (F(1,22) = 0.97, P = 0.33, ŋp2 = 0.04). This critical result was confirmed by a Bayes factor of 0.38, indicating low confidence in this difference. Accordingly, the plain and no-stimulus conditions were averaged, and the branded pack enhanced tobacco-seeking above this average (F(1,22) = 7.23, P = 0.01, ŋp2 = 0.25). The failure of the plain packs to elicit tobacco-seeking in the PIT test, in contrast to branded packs, demonstrates that the discriminative control function of plain packs is degraded.